Referring to FIG. 1, the basic imaging process of a laser printer with a processing cartridge 100 as a core component is as below: a cylindrical surface of a photosensitive drum 101 is charged evenly by a charging roller 102; a laser scanner 103 emits a modulated laser beam 104 carrying image information to the cylindrical surface of the photosensitive drum 101; after illuminating by the laser beam 104, the cylindrical surface of the photosensitive drum 101 is formed with an uneven static charge distribution pattern, namely, an electrostatic latent image corresponding to an image to be copied; then, a developer, such as toner 106, which is conveyed by a developing roller 105 and whose layer thickness has been adjusted by a toner discharging blade 113, is attracted to the cylindrical surface of the photosensitive drum 101, converting the electrostatic latent image into a visible image visible to naked eyes by covering the same; as the photosensitive drum 101 rotates, the visible image formed on the surface of the photosensitive drum by the toner 106 is transferred to a transferring roller 107; by applying a transfer voltage carried by the transferring roller 107, toner in the form of the visible image is transferred to a surface of a recording medium 108 such as paper; after heating and pressing the toner in the form of the visible image on the recording medium 108 by a heating roller 111 and a pressing roller 112, the toner penetrates into fiber layers of the recording medium 108, so that the toner in the form of the visible image is solidified on the recording medium 108 permanently; after the visible image on the photosensitive drum 101 is transferred by the transferring roller 107, waste toner 109 attached to the photosensitive drum 101 is scraped into a waste toner collecting tank by a waste toner scraper 110; the surface of the photosensitive drum 101 is returned to a standby state free from electricity and toner after the static charges are removed by an electricity dissipation device. Thus, a basic imaging process is finished. By repeating the above process, images required by a user can be obtained.